Tag Archives: Weddell Sea

CLIMATE CHANGE

9 Mar

When William Speirs Bruce planned his 1902-1904 expedition to Antarctica his primary ambition was science, as opposed to exploration.

In 1903 he built two scientific observatories on Laurie Island on the northern edge of the Weddell Sea. This was the start of a collection of scientific records that was continued, when Bruce left the Weddell Sea, by the Argentine. Recordings have now been made for 116 years. They continue today providing unique information about meteorological, magnetic and oceanographic conditions in Antarctica.

In relation to meteorology, this graph running from 1903 to 2020 shows the trend and variance in the mean annual temperature on Laurie Island. It is by far the longest recording of temperature in the region (the second longest being from Argentine Islands off the Antarctic peninsula which runs from the early 1950s). As can be seen there is a trend in temperature from – 5°C to -3°C. The graph also illustrates clearly the variability in the annual records, but it is clear that the twenty-first century recordings approximate to the upper recordings in the early 1900s.

This graph would never be available save for William Speirs Bruce’s foresight in encouraging a network of weather stations to be run continuously in the South Atlantic.

 

World temperature is rising, controversy persists, though not amongst the scientists, as to how much man is contributing to the problem.

The reason there is life on our planet relates to infra-red active gases (carbon dioxide, methane, water vapour that are in the stratosphere). The lack of these gases would result in a significantly colder climate, a permanent ice age. Conversely, a rise in infra-red gases would result in a rise in temperature, though there is a complex, non linear relationship between small changes in carbon-dioxide, methane and other trace gases, and the consequent temperature rise. The global climate system is complex which makes it difficult to simply ascribe cause and effect.

But carbon dioxide levels do have a strong correlation to mean global temperatures. Fascinating ice core records were first recovered from the Russian station Vostok which provided records covering 450,000 years. More recently a record of 800,000 years has been recovered from “Dome C” in Antarctica (part of The European Project for Ice Coring in Antarctica). This shows, very clearly, the link between temperature and carbon dioxide levels over cycles of glacial and interglacial periods of around 100,000 years. This is a natural process linked to long term small variations in the Earth’s orbit and axis of rotation. The level of CO2 in the stratosphere has varied naturally between around 180 ppm during glaciations to 280ppm in the warm interglacials, as shown in the records.

                        It has now passed 408 ppm.

Carbon is ubiquitous, in fossil fuels (oil, natural gas, coal), in organic matter in soil and in rock, in the sea. Carbon dioxide is emitted when we exhale, When fossil fuels, are burned carbon dioxide is produced. In 2019 the global emission was 33 gigatons (a gigaton is one billion ).

In the oceans it is estimated that there are billions of metric tons of carbon and further billions of metric tons in sediments on the sea bed. The latter comes from the shells of marine creatures that have absorbed carbon from the water, sunk to the ocean floor and later formed sedimentary rocks.

A raised carbon dioxide level relates to a rise atmospheric temperature which in turn is associated with a rise in ocean temperature, seawater expansion and a rise in water level. The increased water levels are also contributed to by melting land ice and erosion of ice shelf bases. Ice shelves hold ice from flowing outwards and thinning of these shelves increases the flow of ice seawards. An estimated ice loss across the entire Antarctic continent was 43 gigatons each year on average from 1992 to 2002. The loss has accelerated between 2012 to 2017.

Potential results of sea-level rise are coastal erosion and damage. Subsequently, inland areas would become affected and the soil contaminated. If the rise continues toward one metre, some of the world’s major cities will come under threat and even low-lying countries such as Bangladesh, will be threatened.

Ocean acidification, due to dissolved carbon dioxide, has serious consequences.

Acidification affects the southern Krill population. Krill, an essential primary food source, are small crustaceans that feed on zooplankton and convert this into a form suitable for larger animals such as whales, seals, penguins, squid, and fish to eat. All Antarctic wildlife ether depends on krill or depends on something that eats krill for survival. Without this stable base, the food chain linking upwards would deteriorate and eventually collapse. In addition, cold-water corals, which have calcium carbonate in their shells, become less able to build their shells and breeding grounds for both fishes and mammals would be lost.

But some do not subscribe to the concept of global warming, for example: Donald Trump cast doubt on a U.S government report warning of the devastating effects of climate change. When he was asked if unchecked global warming would wreak havoc on the US economy, he said: “I don’t believe it.” The administration has pursued a pro-fossil fuels agenda.

But if conclusions such as this from the U.S. President are wrong, the price to pay is huge. Given the persistence time of CO2 in the stratosphere of 100 years, even if the world were to stop all emission now there is still that legacy which is likely to take the planet past the 1.5 degrees C warming, which scientists say we should not pass. Currently carbon emissions from fossil fuel burning are steadily rising, rather than decreasing. Scientists warn that we are playing dice with the future of humanity.

A final point – global human population increase. This is approximately 83 million annually, or 1.1% per year. Population numbers have grown from a billion in 1800 to approximately 7.616 billion in 2018. Improved medical care and reduced child mortality would be a powerful incentive for families to have the confidence to limit the size of their families.

Policies now direct to keeping carbon emissions flat until 2050. But so far there is little sign of sufficient practical action on this. Scientists are now increasingly coming to the conclusion that we need to go “carbon negative”, which raises the possibility of large scale “geo-engineering”. – Geo-engineering is defined by as the large-scale manipulation of a specific process central to controlling earth’s climate, for the purpose of obtaining a specific benefit (Britannica .com).

Millions now do understand the dangers of global warming and the urgency to contain it. Humanity is at a crossroads, for the sake of our grand-children we need to make the right turn.

 

With grateful acknowledgement for the comments by John Dudeney O B E.-  my co-author of ‘William Speirs Bruce, Forgotten Polar Hero’

 

THE WEDDELL SEA AGAIN

2 Jan

Happy New Year!!

This January, Professor Julian Dowdeswell of the Scott Polar Research Institute will lead an international research team in the long planned expedition to the Weddell Sea. This expedition aims to investigate ice shelves around the Weddell Sea, particularly the Larsen C Ice Shelf. It also hopes to locate the wreck of Shackleton’s ship Endurance, which sank in the area in 1915.

The expedition’s progress and achievements will be followed internationally – in addition the Royal Geographical Society has created an educational programme aimed at engaging the interest of children from primary level upwards.

The Weddell Sea was discovered in 1823 by James Weddell, the British sea captain/ sealer, who sailed as far south as 74°15´S. It is a vitally important ecosystem – penguins, seals, whales, krill, corals and sponges thrive there. It is shaped as a huge bay; Coats Land (discovered by William Speirs Bruce in 1904) is at one extremity, the Antarctic Peninsula is on the other. It has been described as ‘the most treacherous and dismal region on earth’.[i]

An important aim will be to investigate the shapes of the ice shelf bases. Ice shelves stop ice from flowing outwards from the continent. Thinning of the ice shelves results in increased flow from the interior, which, in turn, causes a rising global sea level. The sea floor will be examined to assess the stability of the ice shelf.

Although the general circulation of oceans is determined by wind driven currents, the Weddell is one of few locations where deep and bottom water masses contribute to global thermohaline circulation. Bottom water is the lowest water mass with distinct characteristics in terms of physics, chemistry, and ecology and a temperature of -0.7 °C or colder. The thermohaline circulation is the motor of deep ocean currents and is driven by density gradients influenced by surface heat and freshwater fluxes. The description relates to thermo- temperature-and –haline, salt content.

The Larsen Ice Shelf, in the northwest part of the Weddell Sea, is named after Captain Carl Anton Larsen, master of a Norwegian whaling vessel who sailed along the ice front as far as 68°10′ S. in 1893. From north to south segments of the shelf are called Larsen A, B, and C (the largest), and Larsen D, E, F and G.

The 2019 expedition is focused on the Larsen C ice shelf from which a giant ice berg calved off in July 2017 (twice the area of Luxembourg), reducing the size of the iceshelf by approximately12%.

 

 

 

Dowdeswell and Shears[ii] explain in the ‘Geographical’ that measurements will be taken of salinity and temperature of the sea adjacent to the shelves, samples of marine life will be obtained and the sea ice thickness will be measured by aerial drones. Autonomous Underwater Vehicles will make echo soundings of the underwater shape of the ice shelf base, the roughness of which is a vital parameter in numerical modelling of future ice shelf stability. Ernest Shackleton’s Ship will be searched for.

Whether the team will be able to achieve these aims is uncertain — the conditions are so unpredictable that attempts to navigate south could be unsuccessful, but this expedition is of pivotal importance in attempting to obtain long-term prognostic information relating to global warming. I hope this important analysis of the Weddell Sea will be successfully accomplished.

[i] Henry, T.R.,1950,The White Continent

[ii] Dowdeswell, J. Shears, J. 2019, Geographical, p.10

 

 

 

 

Recognition for William Speirs Bruce

30 May

I have just spent another five days in Edinburgh; at the National Museum and the Edinburgh University Library, continuing my researches on William Speirs Bruce. I find it truly amazing how much information there is on the man, but how little his name is recognised — even in Edinburgh!
Now however, he has received some public recognition. His major contribution to Science was the ‘Scotia’ Expedition, which went to the Weddell Sea and wintered in the South Orkneys. The expedition was successful scientifically: discoveries that were made changed the way the geography of Antarctica was understood, the seas around the Antarctic were explored, a scientific base was set up on South Georgia (which continues today), 1100 species of animal were catalogued of which 212 of them were previously unknown, miles & miles of unknown ocean were explored.
When he returned to Edinburgh Bruce needed to house Scotia’s Antarctic data and specimens. Also, he needed to amalgamate this collection with collections he had made previously on five visits to Arctic. He took a storage area, contiguous with The Surgeons Hall of the Royal College of Surgeons, which he named the Scottish Ocenographical Laboratory, and from here, he worked endlessly and tirelessly in the preparation of six scientific volumes, and a log book,the seventh,which was on the day to day activities of the voyage, This was a Herculean task and took years and years of work. The scientific volumes were published between 1909 and 1920. Bruce’s Log, the narrative of the voyage, was not published until 1992.
The Oceanographic Laboratory had to be closed due to lack of funds before Bruce died in 1921 and, after his death, Bruce drifted into obscurity in the minds of the general public,
Now however, and at last, Bruce has been recognised by the naming of a laboratory at the British Antarctic Survey Research Station on Signy Island in the South Georgia Islands. A commemorative plaque has been erected in the laboratory. The news was given to Bruce’s great, great grandsons at a meeting hosted by the Oban-based Scottish Association for Marine Science in its William Speirs Bruce lecture room.
Dr John Dudeney, an Antarctic specialist, made the approach to the Brutish Antarctic Survey. It is a long needed recognition for one, who struggled ceaselessly, and with insufficient funds, to draw public attention to the wonders and opportunities of Antarctica.

WILLIAM SPEIRS BRUCE

14 Oct

I have now started work on Bruce who led the ‘Scotia’ expedition (1902-04), a scientific expedition in the South Orkneys and the Weddell Sea. I would welcome any input.
Bruce seems to have had two outstanding enthusiasms; Firstly, natural sciences (he gave up the medical studies that he seems to have pursued in a desultory fashion for some years, to embrace the financial uncertainties of a scientific future) and secondly, a passionate Scottish Nationalism.
There are no obvious indicators for these passions;although Bruce’s father Samuel was born in Edinburgh, he grew up in London. Bruce himself was English born and educated. His overwhelming interest in natural science and Scotland seems to have started when he attended summer courses in biology in Edinburgh. These were organised by the inspirational Patrick Geddes. Geddes was an ecologist and promoted a holistic approach to the environment. In these courses Bruce met the foremost natural scientists of the day. His imagination and enthusiasm were caught. Aged 20, Scotland became his home and had his longterm loyalty.
Bitterness towards the South came later, no doubt fueled by Sir Clements Markham’s provocative reply to Bruce’s announcement, in 1901, that he planned a Scottish expedition to Antarctica to leave at roughly at the same time as Sir Clements’ baby. S.S ‘Discovery’
Sir Clements wrote…..’I do not understand why this mischievous rivalry should have been started and I trust you will not connect yourself with it…..’
Such comments inevitably stiffened the determination of the Scottish supporters of the scheme. ‘Scotia’ unusually, was fully financed by private, mostly Scottish backers.
The expedition was a success scientifically and a new land was discovered in the east of the Weddell Sea. He called this Coats Land after his principle backers.
Beyond Scottish borders Bruce is not as well known as other British explorers of the Heroic Era, although Professor David Munro mounted an important celebratory centenary exhibition.
Bruce deserves more recognition

Shipworms

27 Aug

Shipworms which destroy wood. do not survive in Antarctic waters. This is because a Front, at the junction of the polar and warmer waters (as well as currents that circulate round the continent), acts as a barrier that blocks the invasion of these destructive mollusks.

When a Norwegian study led by Thomas Dahlgreen, (1), left wood on the Antarctic shelf for over a year, the wooden planks remained intact.

Trees have not grown on the continent for millions of years and it seems that off shore Antarctica is an inhospitable habitat for wood borers.

The fascinating question is whether wrecks in the Weddell Sea could be recovered. The prospect seems remote, given the depth of the Weddell Sea and the pack ice, but nevertheless the suggestion remains a tantalising prospect. When Shackleton’s ‘Endurance’ was crushed by the pack and sunk in November 1915 (She’s going, boys), she was thought to be lost irrevocably. Could she still be lying, crushed but defiant under the Antarctic waters?

(1) Thomas Dahlgreen. Proceedings of the Royal Society. August, 2013